Cartilage tissues have little self-repair capacity. Defects in cartilage tissues naturally heal to a limited degree with fibrocartilage, the biochemical, mechanical, and physilogical properties of which are inferior to those of normal cartilage. Thus, damaged cartilage tissues are predisposed to degeneration.
Current therapies for cartilage regeneration include carbon plugs, periosteum, periochondrium, subchondral drilling, and autologous chondrocyte transplantation. However, most of them have failed to improve cartilage mechanics or physiology more than natural repair. The clinical need for improved treatment options has led to the development of cartilage implants fabricated in vitro from isolated chondrocytes or mesenchymal stem cells.